“I don’t know of any case where it is done that it doesn’t result in very dramatic benefits of cost reduction. It’s not ‘beat-up-your-supplier-type’ cost reduction, it’s an improved product that’s easy and less expensive to manufacture and assemble,” says John Gillian of a methodology that’s been developed. Given those results—which Gillian says are rather typical of what’s achieved, not some special cases—and given the efforts that are being made by OEMs and suppliers alike to cut costs and to hasten new products to the market, you’d think that this methodology would be more popular than ice water in Hell. (Not that we’re suggesting that there are necessarily any analogies between the Netherworld and the auto industry, although I’m sure that you can think of several points of commonality.)

In point of fact, the methodology that Gillian is talking about is something that you’ve probably heard of and possibly may be familiar with because it has been around since 1983. Gillian is the president of Boothroyd-Dewhurst, Inc. (Wakefield, RI; www.dfma.com); the methodology was developed and transformed into a software package by Professors Geoffrey Boothroyd and Peter Dewhurst...back in the early ‘80s. They received a National Medal of Technology for their work in 1991 from the first President Bush. Yes, design for assembly (DFA) has been around for quite a while.

But it seems as though two things have happened. One is that while many companies may have deployed the method, it has gone by the wayside. Even though if asked whether they do DFA or not they’d undoubtedly say, “Um, yes, ah, of course we do.” The second thing is that there have been a multitude of other approaches developed to improve productivity, which have become the flavors of the month. Consequently, things that have been around for decades are discarded. Gillian suggests that it would probably be beneficial to refer to DFA as “lean product development.” Sounds more au courant.

So for those of you who are not familiar with it, here’s what you need to know.

DFA looks at a total product. It is putting a product together and taking it apart and asking a series of questions while doing so. The answers to the questions lead to an assembly time and an assembly cost. One key approach is to consider the parts that make up the assembly in the context of:

Does it move?

Does it need to be a different material than other parts in the assembly? (E.g., if you have a wire, there needs to be the insulator and the conductor, two different materials.)

Does it need to be separate piece for assembly purposes? (E.g., it may be that it is a box that contains other elements and that the top of the box needs to be removed so those other pieces can be put inside.)

“If it meets one of those criteria,” Gillian says, “then it is considered a necessary part. If it doesn’t, it should be considered for elimination from the product.” One has to think about this, it isn’t a sure thing. Fasteners and spacers are the sorts of things that partisans of DFA look at with great skepticism.

“If you combine those questions with the assembly time, then you can see where the high assembly times are, and if the parts don’t meet the criteria, then work to develop the design changes to eliminate the parts by combining their functions into other parts,” he says, adding, “The important part of it is that it gives you a specific and quantifiable way of looking at the product.” While this can be done manually, the software that has been developed provides a boost with regard to the analysis.

One of the problems as regards the implementation of DFA is that people consider the other element that’s often paired with it—DFM, or design for manufacturing. (In fact, you’ll note that the URL for the Boothroyd-Dewhurst website contains the DFMA acronym.) “A lot of companies that say they are doing design for assembly aren’t changing the design. They are doing minor tweaking. It’s almost more like manufacturing process improvements rather than making the sorts of changes to the design that could radically improve the process.”

Or, said more simply: People forget the design part and think only in the context of assembly. Manufacturing people use the tool for process development. But Gillian points out that it is important to involve designers and manufacturing people together.

Gillian points out that if you look at product cost, there are basically three elements. Part cost, labor and overhead. The labor cost—the assembly cost—is generally on the order of four to five percent. Yet people give that most of the attention. How many products are being “outsourced to low-cost countries” because the assemblers are getting paid a few bucks a month? But the part cost, he points out, is generally around 70%. “That’s what DFA attacks.”

“If you can simplify your product during design, you have a lot less to manufacture later,” Gillian points out, adding, “Lean manufacturing can result in single-digit percent improvements. If you improve early in the design stage, you’re talking double-digit percent improvements.”

Conceivably, not only would addressing part design predicated on functionality and assembly mean that it wouldn’t be necessary to send the assembly work overseas, but it could also permit additional invest-ment in the product (e.g., the use of higher-quality material) because of the reduction in cost achieved through the DFA analysis. That, in turn, could lead to more sales, improvement in market share, and...It may no longer be the trendy thing to do, but it surely provides some competitive advan-tages for those who actually do it right.

The Future Is Function

If you want to make a highly precise product, you need to start with highly precise parts, right? You need to have parts that have tight tolerances, with zeros ranging well to the right side of the decimal point, right? One might assume that’s the case. Which could explain, in part, why some products are so expensive. Lots of zeros. Tight tolerances. But Larry Stockline thinks that while it is true that, in his words, “adding zeros adds dollars,” he also maintains that focusing on part tolerances misses the point. His basic question for any assembly, be it a light switch or a transmission: What’s the function? In other words, what is the assembly in question expected to do by the customer? Once that’s determined, then it is a matter of performing the assembly process so that the functional requirements will be fulfilled—100% of the time.Stockline, president of Promess Inc. (www.promessinc.com; Brighton, MI), which makes a variety of sensor-based assembly technology products, explains how he became more focused on function than dimension: “I come from a dimensional world. Being a former machine operator, I would build to print. I used to machine shafts and put in a corner. I would ask why every shaft would have a shoulder. The old timers would chide me and tell me that’s where the bearing goes. They push a bearing to that location, so that location is critical.” So he would be careful to machine to meet the required spec. But, he continues, “I was always intrigued that even though I would make certain things to dimension, at times the parts didn’t work.” Given the variable stack of tolerances—or perhaps the fact that when the bearing was pushed to the shoulder it was damaged—the anticipated performance wasn’t there. The general reaction would be to tighten the tolerances, which makes things more expensive. And not necessarily result in every assembly functioning as anticipated. “No one is assigned to function,” Stockline says. But there is someone assigned to handling the problems when the product doesn’t function. Which leads to things like tremendous warranty costs.

He says the approach in developing an assembly is to start with the function, then to work backwards through the design. “In order to reach that functional need, I could have looser tolerances.” He says that in the cases of 30 to 40% of the products they’ve worked on they’ve been able to loosen tolerances, and consequently reduce costs. But he emphasizes that the products do what they’re supposed to do. There is assurance because Stockline says, “I am a proponent that every part has to go through a test as humans will use it.”

He provides an example of an assembly that one might think would require exceedingly tight tolerances—which is the case if it wasn’t assembled based on function. It is an ABS check valve. Initially, the requirement was to build a valve that would be ±200 psi. To get that, Stockline says, it would be necessary to have a precision spring, a precision ball, and a precision bore that are assembled. But he explains that they took a “normal” spring, ball, and bore, then pressed it to function, which is 1,000 psi. Every time they press the pieces together, they make sure that the assembly functions at 1,000 psi. “We are physically making the check valves to function. Before it was all to dimension. We took 20% out of the cost.”